Immobilisation of the knee and ankle and its impact on drivers’ braking times

Abstract

The purpose of this study was to investigate the effects of right leg restriction at the knee, ankle or both, on a driver's braking times. Previous studies have not investigated the effects of knee restriction on braking performance. A total of 23 healthy drivers performed a series of emergency braking tests in a driving simulator in either an above-knee plaster cast, a below-knee cast, or in a knee brace with an increasing range of restriction. The study showed that total braking reaction time was significantly longer when wearing an above-knee plaster cast, a below-knee plaster cast or a knee brace fixed at 0°, compared with braking normally (p < 0.001). Increases in the time taken to move the foot from the accelerator to the brake accounted for some of the increase in the total braking reaction time. Unexpectedly, thinking time also increased with the level of restriction (p < 0.001). The increase in braking time with an above-knee plaster cast in this study would increase the stopping distance at 30 miles per hour by almost 3 m. These results suggest that all patients wearing any lower-limb plaster cast or knee brace are significantly impaired in their ability to perform an emergency stop. We suggest changes to the legislation to prevent patients from driving with lower-limb plaster casts or knee braces.

When Can I Drive After Orthopaedic Surgery? A Systematic Review

“…Patients with THAs had normal brake response times, total brake times, and brake forces 2 to 8 weeks after right-sided procedures [15,23,30,39,53] and 1 to 8 weeks after left-sided procedures [15,30,39]. Driving measures such as brake response time, total brake time, and brake force were significantly impaired when a driver wore a right lower-extremity hard cast, aerated orthosis, controlled ankle-motion cast, short leg cast, above-or belowknee plaster cast, or ROM-restricting brace [10,48,60,63].…”

How do ankle braces affect braking performance? An experimental driving simulation study with healthy volunteers

“…This could be explained by the grade of immobilization of the ankle, which in Orr's study greatly exceeds the immobilization when wearing only an ankle brace. This phenomenon was investigated in detail by Waton et al (23), who tested the effect of gradual immobilization of the knee using a DonJoy ® knee brace (DJO Inc. ® ) adjusted in 30° steps from 90° flexion to 0° immobilization, and both a below-and above-knee plaster. As expected, a gradual increase in immobilization resulted in a gradual increase in FTT and Mean differences with 95% confidence intervals for all pair-wise comparisons of measurements without brace minus each intervention group and calculated increased stopping distance at 100 km/h.…”

“…First, it could be due to the reduced weight of Kallassy ® compared with the other braces. Secondly, it could be explained by the phenomenon described by Waton et al (23); while CaligaLoc ® , Air-Stirrup ® and ASO ® are made of non-elastic material and therefore provide a more rigid fixation, the Kallassy ® boot is made of a neoprene-like fabric, which increases wearing comfort. However, in our opinion, this leads to less restriction of movement than with the other braces investigated in this study.…”

“…Various studies have investigated the effect of surgical procedures. However, there is limited information available regarding the influence of an immobilized lower limb on driving fitness (20)(21)(22)(23).…”

“…Based on the findings of Waton et al (23), it was expected that braces immobilizing the ankle would affect braking performance. However, in a study published by Tremblay et al (22) BRT was prolonged by only approximately 5% when immobilizing the ankle.…”